Open cluster
M46 (M46)
In Puppis (Pup) • Magnitude 6.0 • 27 arcminutes
Open the free AstroPlanner with M46 pre-selected, scored against your telescope, location, and the live cloud forecast.
A rich open cluster in Puppis with an extraordinary bonus — a planetary nebula (NGC 2438) appears superimposed on it. The nebula is not actually related to the cluster; it just happens to sit along the same line of sight, thousands of light-years closer to us, in one of astronomy's great accidental coincidences.
M46 at a glance
| Catalog IDs | M46, N 2437 |
| Type | Open cluster |
| Constellation | Puppis (Pup) |
| Right ascension | 07h 41m 49s |
| Declination | -14° 49' 12" |
| Apparent magnitude | 6.00 |
| Angular size | 27.0 × 27.0 arcmin |
| Max altitude at 45°N | 30° |
| Best imaging months | Oct, Nov, Dec |
How to image M46
M46 sits in the constellation Puppis at right ascension 07h 41m 49s and declination -14° 49' 12". To frame and integrate it well, AstroPlanner will compute the optimal moonless window for tonight from your location, the field-of-view fit against your sensor and focal length, the suggested total integration time given your aperture and sky Bortle class, and a cloud-aware schedule that drops it from the plan if your nearest cloud forecast spike overlaps the best altitude window.